remove comment
Fix a couple of basic typo bugs w.r.t. job stopping
Add new method `load_samples` which will take an arbitrary list of sample paths and pre-load them all

This means that when they are used for the first time , there will no
delay when loading them, so they will be triggered on time.
Add new test for jobs stopping - also move quit-on-exit hook to the 
top of the file to ensure it's registered before any errors!